Steven
Questions:1
Answers:42
Best Answers:12

The main purpose of armour is to provide mechanical protection, although it can also provide part of the earth fault path. For multi-core cables steel wire armour is most often used. Single core cables produce a magnetic field which induce current and losses in steel; aluminium being non-magnetic is used with these cables.

It doesn’t really depend on voltage or frequency. At higher voltages you have higher magnetic fields which would give bigger problems if you used steel wire on a single core cable instead of aluminium. Earthing does not affect it; however you should always ensure the armour is earthed at a supply end, to prevent it becoming live in the event of a fault.